Insulation for buildings is faced with a flame retardant material that serves a dual purpose of acting as a vapor barrier and as a flame retardant material. The facing is adhered to the insulation, for example fiberglass insulation batts of varying thickness. Typically the facing is laminated to a single side of the insulation batt, although in particular applications the facing is laminated to both sides of insulating material. Most common are insulating batts of needled fiberglass.
The insulation and adhered insulation facing must pass flame retardant testing by independent test organizations such as Underwriter Laboratories (UL). A standard flame test is ASTM E-84. In order to pass this test, a flame spread index of less than 25 is required. Flame spread testing is also specified in Underwriters' Laboratories Standard for Safety UL-723 (also Underwriters' Laboratories of Canada Standard for Safety ULC-S102M) that requires a flame spread index of less than 25 and the smoke developed index of less than 50. Standard UL-723 specifies a test during which a material is exposed to a calibrated flame that produces a flame spread along the entire length of a red oak flooring calibration specimen in 5.5 minutes (red oak has a flame spread index of approximately 91). The Smoke Developed index compares smoke to that of red oak (red oak has a smoke developed index of approximately 100).
Previously used as facing products are composite laminates having Kraft paper layers, foil or metallized film, synthetic fiber reinforcing arrays and adhesive layers. Such facing materials are not “recyclable” due to the difficulty in separating the components of the laminates.
Popular examples of existing facing products are available from Lamtec Corporation under the WMP trademark. For example, Lamtec product WMP-10® consists of a Kraft paper layer, a metallized polypropylene layer, fiberglass/polyester reinforcing array and flame retardant adhesive. While WMP-10® meets flame spread tests, it is subject to failure due to physical attributes. It is not uncommon for WMP-10® facing to become torn or damaged by personnel unloading insulation at a construction site. Once the facing is torn or punctured, the vapor barrier is no longer effective.
Further, currently available facing products are somewhat difficult to install because the layer that lends body to the facing, typically scrim, lacks strength and recyclability due to the mixture of polymer and paper. When used in metal building insulation, the insulation facing is inadequate to support the weight of installing personnel. Either additional safety barriers or use of personnel lifts are required during installation. U.S. Pat. No. 6,094,883 to Atkins discloses examples of such a safety barrier.
Higher tensile strength is also beneficial for installation of insulation in metal buildings. It is customary to lay the faced insulation between roof and wall purlins and then apply tension to the insulation to produce a smooth, aesthetically pleasing appearance. Insulation having higher tensile strength is preferable during the stretching phase of installation as well as reducing sagging in the final installed insulation. U.S. Pat. No. 4,972,644 to Rumiesz, Jr. et al. discloses an insulation product of insulation batts adhered to insulation facing. U.S. Pat. No. 4,365,767 to Benthimere discloses an apparatus for adhering the facing material to the insulation batts.
Many of the facing strength deficiencies could be overcome by use of a polyolefin woven substrate. Woven substrates are capable of many times the bursting strength of facing products such as WMP-10®. When attached using staples, and the like, woven substrates are also much more resistant to staple pull-throughs.
In order to provide a vapor barrier a polyolefin woven substrate is coated with a flame retardant vapor barrier. The coating is preferably of a similar polyolefin as the substrate in order to aid recyclability. However, prior attempts at using coated polyolefin woven substrates have been unsuccessful in producing insulation facing that satisfies flame spread and smoke generation tests when the facing is laminated to the insulation.
The inventors have surprisingly discovered that a failure resistant flame retardant insulation facing can be beneficially manufactured by limiting the vapor coating to the side not adhered to the insulation. Such a facing product comprises a woven polyolefin substrate with one or more layers of vapor barrier applied to the substrate surface facing away from the insulation it is adhered to.
In contrast, a product with a polymeric layer on two sides typically fails the flame spread and smoke generation tests, particularly the flame spread test. The inner coating adhered to the insulation provides a path for the flame to spread down a tunnel formed by the facing.
Known in the art are methods for adhering insulation facing materials to insulation. Typical is the use of latex adhesives, for example those available from National Starch. For a successful insulation material, a sample comprising the facing adhered to the insulation must pass required flame spread and smoke generation standards.
What is desired is a flame retardant facing that will pass flame spread testing, will provide a vapor barrier, and have sufficient physical properties to resist tearing, bursting, puncturing and is recyclable.